How many times can I split a coaxial cable.

[mztang52]

Hi guys, I want to run a small cable ISP. I want to know how many times can I split a coaxial cable? I want to supply 15mbps for every user and I'm going to use RG-6U cable. I want to split a coxial cable to 200 houses. Is it possible? Do I need any low noise amplifier?

[thekeemo]

200!

At that point im worried about signal degradation because of the signal not the splitting.

[mztang52]

1 minute ago, thekeemo said:

200!

At that point im worried about signal degradation because of the signal not the splitting.

Will the signal affect the speed? Because I'm not going to provide Cable TV service as it will cause noises.

[thekeemo]

7 minutes ago, mztang52 said:

Will the signal affect the speed? Because I'm not going to provide Cable TV service as it will cause noises.

Yes. Found this

Quote

For a typical digital TV signal in the UHF range with RG-6 coaxial cable, you can figure 1.4 - 2.0 dB loss per 100 foot. Also, remember that each connector results in an additional 3 dB loss.

You also have to factor in distance from the pole

[mztang52]

11 minutes ago, thekeemo said:

Yes. Found this

You also have to factor in distance from the pole

How much will it affect?

[thekeemo]

Just now, mztang52 said:

How much will it affect?

Give me numbers to work with.

[tt2468]

1 minute ago, thekeemo said:

Give me numbers to work with.

There are no numbers. You can calculate some numbers by taking the resistance of each splitter, and adding them together, then getting a signal powerful enough to reach the last client on the chain.

[mztang52]

5 minutes ago, tt2468 said:

There are no numbers. You can calculate some numbers by taking the resistance of each splitter, and adding them together, then getting a signal powerful enough to reach the last client on the chain.

So should I use low noise spliter or high power spliter

[ionbasa]

Not gonna work with RG-6U

 

First you're gonna need a headend, cmts, trunk coax (CommScope), various taps, a node or two, and some amps.

Have a field day: http://www.vikimatic.com/

 

DOCSIS 3 CMTS: $12k Motorolla BSR64000HD -Used price off of ebay

^^^I'll stop there, there's no point in going any further. We're talking about at least an 1/2 million dollar project. 

 

If you really need to ask here on a forum, you shouldn't even be thinking about this. 

 

Source: I work for an civil engineering and planning company. Worked with utilities before, seen the BOM, it's not pretty. Good luck getting planning approval from the city and county, along with approval of renting/buying utility pole space (yes, there's a fee for that too).

[tt2468]

5 minutes ago, ionbasa said:

Not gonna work with RG-6U

 

First you're gonna need a headend, cmts, trunk coax (CommScope), various taps, a node or two, and some amps.

Have a field day: http://www.vikimatic.com/

 

DOCSIS 3 CMTS: $12k Motorolla BSR64000HD -Used price off of ebay

^^^I'll stop there, there's no point in going any further. We're talking about at least an 1/2 million dollar project. 

 

If you really need to ask here on a forum, you shouldn't even be thinking about this. 

 

Source: I work for an civil engineering and planning company. Worked with utilities before, seen the BOM, it's not pretty. Good luck getting planning approval from the city and county, along with approval of renting/buying utility pole space (yes, there's a fee for that too).

Hes providing TV, not internet. A much more simple setup

[ionbasa]

Just now, tt2468 said:

Hes providing TV, not internet. A much more simple setup

From OP:

38 minutes ago, mztang52 said:

Hi guys, I want to run a small cable ISP. I want to know how many times can I split a coaxial cable? I want to supply 15mbps for every user and I'm going to use RG-6U cable. I want to split a coxial cable to 200 houses. Is it possible? Do I need any low noise amplifier?

 

[tt2468]

4 minutes ago, ionbasa said:

 

 

Oops

[thekeemo]

7 minutes ago, ionbasa said:

Not gonna work with RG-6U

 

First you're gonna need a headend, cmts, trunk coax (CommScope), various taps, a node or two, and some amps.

Have a field day: http://www.vikimatic.com/

 

DOCSIS 3 CMTS: $12k Motorolla BSR64000HD -Used price off of ebay

^^^I'll stop there, there's no point in going any further. We're talking about at least an 1/2 million dollar project. 

 

If you really need to ask here on a forum, you shouldn't even be thinking about this. 

 

Source: I work for an civil engineering and planning company. Worked with utilities before, seen the BOM, it's not pretty. Good luck getting planning approval from the city and county, along with approval of renting/buying utility pole space (yes, there's a fee for that too).

I think it is an off the books thing in the middle of nowhere.

[ionbasa]

19 minutes ago, thekeemo said:

I think it is an off the books thing in the middle of nowhere.

Ok, but how's he gonna tie in to the Internet (tier 1/2 providers) in the middle of nowhere?

 

15Mbps *2 symmetrical upload * 200 houses = 6 Gbps not accounting for overhead. He's not gonna do that with just 1 cmts/headend.

 

As an thought experiment though: 

200 homes in an residential area, let's assume we need less than a mile of cable. The minimum spacing between homes is 10 feet (CA building code). (5 ft from the edge of an structure to the property line). Meaning:

 

200 homes * 10 feet spacing = 2000 ft or .37 miles of trunk cabling under ideal situations.

 

DOCSIS 3 operates arround 750 Mhz

The dB loss for 2000 ft of trunk cable at 750 Mhz is 112.4 dB

 

Not including the taps and splitters needed. Assuming 1 tap per drop (from trunk cable to home). An typical coax tap is about 10db loss. 

 

 

 

What the OP wants is technically not feasible. Even big cable companies have to use fiber to the node to compensate for this (HFC).

[vanished]

I don't want to offend anyone, but it just seems like if you are planning on starting and running your own ISP for 200 customers, you, or someone you hire should probably know this stuff.

[ionbasa]

9 minutes ago, Ryan_Vickers said:

I don't want to offend anyone, but it just seems like if you are planning on starting and running your own ISP for 200 customers, you, or someone you hire should probably know this stuff.

Agreed. It's not just the technical aspect of it, but also the legal aspect. You can't just wake up one morning and start running your own coax trunk cables on utility poles. 

 

This isn't the right place to even begin asking about this stuff. I'm not a cable engineer myslef (mechanical engineer), but asking on LTT is like trying to get an answer to an calculus problem from an kindergarden classroom (no offense to LTT), this just isn't the right outlet. 

 

A better option (if he's actually gonna go through with it) would be to try a contact a real professional via: http://www.scte.org/ from an nearby chapter. 

[thekeemo]

18 minutes ago, ionbasa said:

Ok, but how's he gonna tie in to the Internet (tier 1/2 providers) in the middle of nowhere?

 

15Mbps *2 symmetrical upload * 200 houses = 6 Gbps not accounting for overhead. He's not gonna do that with just 1 cmts/headend.

 

As an thought experiment though: 

200 homes in an residential area, let's assume we need less than a mile of cable. The minimum spacing between homes is 10 feet (CA building code). (5 ft from the edge of an structure to the property line). Meaning:

 

200 homes * 10 feet spacing = 2000 ft or .37 miles of trunk cabling under ideal situations.

 

DOCSIS 3 operates arround 750 Mhz

The dB loss for 2000 ft of trunk cable at 750 Mhz is 112.4 dB

 

Not including the taps and splitters needed. Assuming 1 tap per drop (from trunk cable to home). An typical coax tap is about 10db loss. 

 

 

 

What the OP wants is technically not feasible. Even big cable companies have to use fiber to the node to compensate for this (HFC).

We fan assume apartment block and not the middle of nowhere (common practice in Egypt) if he splices wire (even possible with coax??) instead of using switches it might work.

[ionbasa]

Just now, thekeemo said:

We fan assume apartment block and not the middle of nowhere (common practice in Egypt) if he splices wire (even possible with coax??) instead of using switches it might work.

Still unrealistic for 1 coax line? You'd saturate the total bandwidth of the connection even with channel bonding of DOCSIS and QAM modulation. 6Gbps on one RG-6U coax cable is kinda asking for a lot.

 

And we even haven't started talking about cable impedance, ingress, noise, SNR, etc.  

[thekeemo]

6 minutes ago, ionbasa said:

Still unrealistic for 1 coax line? You'd saturate the total bandwidth of the connection even with channel bonding of DOCSIS and QAM modulation. 6Gbps on one RG-6U coax cable is kinda asking for a lot.

 

And we even haven't started talking about cable impedance, ingress, noise, SNR, etc.  

We can definitely agree on this being a horrible idea if done via 1 coax. If I had to use coax I would probably run 20 lines with a active splitter.

[ionbasa]

19 minutes ago, thekeemo said:

We can definitely agree on this being a horrible idea if done via 1 coax. If I had to use coax I would probably run 20 lines with a active splitter.

It might be cheaper to run a fiber or ethernet drop to each house/apartment and do some VLAN and trunking magic. Takes COAX, cable modems, CMTS'es out of the equation. Fiber is pretty cheap nowadays anyways. And you don't need any fancy equipment.

[brwainer]

I work for a small-ish ISP (~100,000 users) and we support a almost 100 seperate cable systems. Only one of them is cable modem internet, the rest are purely TV service, but the low level of getting enough signal to each connected device (TV, modem) is the same. I have been involved in several new installation projects, both in planning and installing the hardware. With this experience, I would barely be able to plan a new system on my own. While it is good that you are curious and want to make a new service for your community, I highly advice you to at the very least hire a cable engineer as a consultant.

 

That being said, I will try to answer the original question. From a downstream signal perspective (that is, from the CMTS to the modems) you can basically split it as many times as you want, with good quality splitters and amplifiers. You'll need a lot of amplifiers and/or powered splitters though. From an upstream perspective, the amplifiers should do reverse amplification of the low frequency signals used for upload, but there tends to be more of a limit sonce the cable modems output a weaker signal than the CMTS.

 

You don't want to have 200 modems on one cable network. When we set up our one location with cable modem service, we were recommended to put only 100 modems per CMTS. That means you would have two seperate cable networks in your plan, and I would actually split it into three. When people talk about congestion in the cable network for the neighborhood, this is what they are talking about.

 

Unless these 200 modems are all in the same building, you're going to end up needing at least one powered outdoor amplifier, and maybe outdoor splitters. Outdoor cable equipment (and some indoor) is always powered by DC voltage injected into the cable system, This is usually 48V DC but is sometimes 60V or higher.  THIS CAN EASILY KILL YOU BECAUSE IT IS DC. AC IS ACTUALLY SAFER. TRAINED AND EXPERIENCED CABLE AND TELEPHONE ENGINEERS ARE REGULARLY HURT IF THEY OR SOMEONE ELSE MAKES A MISTAKE. ALWAYS ENSURE THE CABLE YOU ARE WORKING ON IS NOT ENERGIZED. Because of this, ALL outside cable plants should be have the proper permits and be installed by trained professionals.

 

(technically it is amperage that kills, not voltage. Higher voltages make it easier for the electrons to jump through your body. DC is more dangerous than AC because it makes your muscles lock up, possibly locking your hand onto the wire or whatever else gave it the shock. AC makes your muscles spasm, so you will usually break contact with the voltage source almost immediately.)